Note 2 - Basis of Presentation and Summary of Significant Accounting Policies - Other Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Other property and equipment, net	$ 1,397	$ 1,092
Land [Member]
Other property and equipment, net	1,122	725
Technology Equipment [Member]
Other property and equipment, net	167	292
Transportation Equipment [Member]
Other property and equipment, net	86	41
Leasehold Improvements [Member]
Other property and equipment, net	13	24
Field Equipment [Member]
Other property and equipment, net	$ 9	$ 10